Digging and carrying scraper



Dec. 11, 1956 E. R. FRYER ET AL DIGGING AND CARRYING SCRAPER m J R 1 mmB YD m mm H m m m M 8 MM 6 Mm @w 2 5 9 l 1 y a M d e l 1 F Arra/P/vrsD12, 111, 1956 E. R. FRYER ET AL 2,773,320 I: v,

DIGGING AND CARRYING SCRAPER Filed May 14, 1952 6 Sheets-Sheet 2 IVENTOR. fowano FRYER WILLIAM J. ADA/16 Dec. 11, 1956 E. R. FRYER ET AL2,773,320

DIGGING AND CARRYING SCRAPER Filed May 14, 1952 a 6 Sheets-Sheet 5INVENTOR. fawn/v0 R. FRYER WILLIAM J: ADAMS A 1- ran -17:

Dec. 11, 1956 E. R. FRYER ETAL 2,7

DIGGING AND CARRYING SCRAPER Filed May 14, 1952 6 Sheets-Sheer. 4

IN VEN TOR. EDWARD R. Fnren Wang! J. Adams AT R EYS 1956 E. R. FR YER ETAL DIGGING AND CARRYING SCRAPER 6 Sheets-Sheet 5 Filed May 14, 1952 IN VEN TOR.

ATTORNEYS Dec. 11, 1956 Filed May 14, 1952 CENTER OF GRAVITY APRON AOADE. R. FRYER ET AL DIGGING AND CARRYING SCRAPER 6 Sheets-Sheet 6INVENTOR. FowA RD Fvxsw WILLIAM 11' AOAMS ATTORNEYS United States PatentDIGGING AND CARRYING SCRAPER Edward R. Fryer, Willoughby, Ohio, andWilliam J.

Adams, Santa Cruz, Califi, assignors, by mesne assigneuts, to GeneralMotors Corporation, Detroit, MiClL,

a corporation of Delaware Application May 14, 1952, Serial No. 287,772 7Claims. (Cl. 37-126) lifting the bowl and actuating the ejector, eachbeing movable independently of the other, wherein each power unit isinterchangeable for obtaining economy in manufacture and servicingwithout sacrificing desirable operational characteristics.

Another object of the present invention is to provide in a digging andcarrying scraper of the type described interchangeable power units, asaforesaid, with each exerting approximately the same force but movingthe apron, bowl or ejector each at a speed commensurate with its loadand over the proper distance for satisfactory performance.

Another object of the present invention is to provide in a digging andcarrying scraper of the type described a pull yoke of continuous boxbeam construction having space for housing means for raising andlowering the bowl and apron while causing minimum interference with thevision of the operator back into the scraper bowl.

Another object of the present invention is to provide in a digging andcarrying scraper of the typedescribed a pull yoke having in a housinghydraulic hoists approximately aligned on vertical axes with spacebetween said hoists and having one or more cutouts in the housingpermitting sight back into the scraper bowl by the operator.

Another objectof the present invention is to provide in a digging andcarrying scraper of the type described a simple, rugged scraper pullyoke eliminating earth spillage, from the heaped scraper load, cloggingup around the apronand bowl-raising means while permitting good visionby the operator back into the scraper bowl.

Another object of the present invention is to provide in a digging andcarrying scraper of the type described an apron movable with respect tothe scraper bowl, power means for raising the apron and novel motiontransmitting means between the power means and the apron for causing theapron to move a larger distance than, but in response to, said powermeans.

Another object of the present invention is to provide in a digging andcarrying scraper of the type described a bowl and a bowl raising meansincluding rigid links having means permitting up float of the bowl.

Another object of the present invention is to provide, in a digging andcarryingscraper of the type described, a bowl and an ejector for dumpingthe contents of said bowl wherein said ejector normally accelerates inmovin between loading and dumping positions as the load is decreased onthe ejector.

Another object of the present invention is to provide in a diggingandcarrying scraper of t hejtype described a scraper bowl, an ejectorpivoted to the bowl, means for raising the ejector from a loadingposition to a dump- "ice ing position approximately balanced over itspivot, and resilient means effective only when said ejector is near thedumping position for moving the ejector oil of the approximatelybalanced position toward said loading position.

Other features of this invention reside in the arrangement and design ofthe parts for carrying out their appropriate functions.

Other objects and advantages of this invention will be apparent from theaccompanying drawings and description and the essential features will beset forth in the appended claims.

In the drawings,

Fig. l is a side elevational View of the lever type digging and carryingscraper in its loading position showing the lines of sight of the driverback toward the scraper bowl during the loading operation;

Fig. 2 is a side elevational view of the digging an carrying scraper ofFig. l in its hauling position showing the lines of sight of the driverback under the scraper bowl so that he can easily check whether or notthe bowl i is properly elevated for hauling;

Fig. 3 is a side elevational view of the digging and carrying scraper ofFig. 1 in its dumping or ejecting and spreading position with the linesof sight of the scraper operator shown thereon;

Pig. 4 is a top plan view of the digging and carrying scraper of Fig. lwith the lines of sight from the operator back into the bowl shownthereon;

Fig. 5 is a top plan view of a portion of the scraper pull yoke shown insolid lines for clarity and of a portion of the bowl and apron raisingmechanism and pressure fluid lines shown in dot-dash lines;

Fig. 6 is a vertical, longitudinal sectional view taken along line 6-6of Fig. 5;

Fig. 7 is a vertical, sectional view taken along line 7-7 of Fig. 6through one of the rearwardly extending diverging box beam arms of thepull yoke;

. Fig. 8 is a vertical, sectional view taken along line 8--8 of Fig. 5through the pentagonal shaped box beam torque tube looking toward one ofthe pull arms;

Fig. 9 is a sectional View taken along the line 99 of Fig. 6 showing oneof the box beam pull arms in cross section and the pressure fluid linetherein in dotdash lines;

Fig. 10 is a side elevational view of the ejector and the mechanismassociated therewith, wherein the ejector is shown in dilferentoperative positions by solid, dotdash, and dot-dot-dash lines; whileFig. 11 is a side elevational view of the digging and carrying scraperwith the bowl partially raised toward its fully elevated haulingposition and disclosing difierent relative dimensions between theoperating scraper parts making possible interchangeability of thehydraulic hoists which operate the. apron, bowl and ejector.

The general construction of the digging and carrying scraper coupledwith a pulling tractor is shown in Figs. 1 to 4 inclusive. A tractor 2thof four-wheel type, having two parallel rear drive wheels 21, is of thegeneral type with an engine in the front connected by the usual changespeed mechanism and drive mechanism with a rear axle for driving therear wheels 21. A pull yoke 22 on the digging and carrying scraper isconnected to the rear of the tractor by a hitch 23 located between rearwheels 21 and providing pivotal connections therehetween extending alonga vertical axis, along a horizontal axis longitudinally with respect tothe length of the tractor frame, and along a horizontal axis transversethereto. This hitch connection may take the form shown in Fig. 3 of thecopending U. S. patent application to William J. Adams, entitledScraper, erial No. 111,496, filed August. 20, 1949 now Patent No.2,674,815, granted April 13, 1954.

The tractor 26 also carries a source of pressure fluid including apressure generating device such as a pump and carries control meanswithin reach of the tractor operator connected with conduits leadingback to the scraped for operation of the moving parts thereof by fluidpressure.

A scraper bowl 24 is pivotally secured to the rear of the pull yoke 22and is formed by spaced apart, vertically extending, substantiallyparallel side walls 24:2, 24a. This scraper bowl has laterally extendingbox beams 24b, 24c and 24d extending between and welded or otherwisesecured to each of the side walls to keep them in the spaced apartrelationship. It should be noted that the front or left-hand side of thescraper bowl in Fig. 3 is substantially open between the side wallsexcept for the strengthening of the box beams 2412. Another box beam242, triangular in cross sectional shape, is located between and weldedor otherwise secured to the side walls at the mid-portion of theirbottoms. Any type cutting blade may be removably secured to thislastmentioned box beam 24@ for digging the earth or other materialduring the loading operation shown in Fig. l and for directing it backinto the scraper bowl. A specific type of cutting blade especiallydesirable for this type of digging and carrying scraper is disclosed ina copending U. S. patent application to Edward R. Fryer, entitled OffsetCutting Edge for Scrapers, Serial No. 226,601, filed May 16, 1951.

A rear support for the scraper bowl 24 is provided. Two upper box beams26, 26, and two lower box beams 27, 27 are each welded or otherwisesecured at their left-hand edge in Figs. 4 and 11 to the rear of thebowl and extend rearwardly to meet on the same horizontal line. A pushbumper 28 is welded or otherwise secured to the rear of each of theafore-mentioned box beams, and this bumper may be engaged by a pushertractor or bulldozer with a pushing force when aiding the loading of thescraper or While the scraper is being push loaded. This pusher bumpermay make the form disclosed in our copending U. S. patent applicationSerial No. 283,949, entitled Pusher Bumper, filed April 23, 1952. A rearaxle housing 30 is welded or otherwise secured to the box beams androtatably supports a pair of spaced rear wheels 31, 31.

The open front of the bowl 24 may either be open, as shown in Fig. 3, orbe closed by an apron 33, as shown in Fig. 2. The apron has an outwardlyconvex, smooth outer or front surface extending downwardly andrearwardly and has a pair of spaced side arms 33a, 33a welded orotherwise secured thereto and straddling the spaced bowl side walls 24a,24:: with the rearward end of each arm pivotally secured to itsrespective bowl side wall so that the apron 33 may be moved between theclosed and open positions shown in Figs. 2 and 3 respectively.

An ejector 34 forms the bottom and rear walls of the scraper bowl andextends between the side walls thereof. It has a bottom wall pivotallyconnected at its front end by a hinge at 34a to the triangular box beam242 behind cutting edge 25 and the open front of the bowl. It also has awall extending upwardly and rearwardly from this bottom wall along asmooth curve to form the rear wall. The ejector 34 can pivot forwardlyand upwardly about pivot 34a for dumping the contents of the bowl.

Pull yoke 22 is shown generally in Figs. 1, 2, 3 and 4 and specificallyin Figs. 5 to 9 inclusive. The pull yoke may be described broadly ashaving a pair of arms rearwardly extending from the hitch 23 with therearward or distal end of each arm being pivotally attached to theoutside of the respective bowl side walls 24a, 24a. A space is leftbetween the arms for housing means for raising the scraper bowl 24 andthe apron 33. Each arm forms a continuous box beam structure from thehitch to the rearward pivotal connection with its associated bowl sidewall to provide a strong, integral structure for lifting and carryingthe forward part of the scraper bowl 24 with the load therein, and forwithstanding all pulling, pushing and backing loads and other strainswhich these large scrapers undergo. Also, the pull yoke is soconstructed that good visibility is always provided back into and aroundthe scraper bowl at all times since the pull yoke causes a minimuminterference with the sight of the tractor driver.

Said broadly defined pair of arms behind said hitch member 23 includes apair of gooseneck arms 40, 41. These arms diverge in the rearwarddirection and have a space provided therebetween for housing hydraulichoists for raising the bowl and apron to be described later in thespecification. Each arm is of box beam construction formed by fourplates welded together, as shown by plates 46a, 40b, 40c and 40d of arm40 in Fig. 7 and correspondingly numbered plates for arm 41. Both theinnermost vertically extending plates 40b and 41b of arms 40 and 41 andthe outermost plates 40a and 41a diverge in the rearward direction. Eacharm is in the form of an upwardly arched gooseneck having sufficientarch for clearing the rear wheels 21, 21 of tractor 20 during turningfor even a turn. v

It should be apparent that arms 40 and 41 could be replaced by analternative construction consisting of a single unitary box beamproviding some but not all of the advantages of the separate arms 40, 41since the rearwardly diverging space shown in Fig. 5 between innerplates 40b and 4112 would not exist. This unitary box beam would haveoutermost plates 40a and 41!; rearwardly diverging but upper plates 40cand 410 and lower plates 40b and 41b would be replaced by a single solidupper plate and a single solid lower plate with each welded to bothouter plates 40a, 41a and bridging the span therebetween to hold thespaced outer plates together. This box beam would have the samerearwardly diverging plates 40a and 410 as arms 40 and 41 and would bedesigned with a cutout to provide a space therebetween for the hydraulichoists for raising the bowl and apron, presently to be described.

To the rear of this diverging portion of the yoke is secured a torquetube welded to the rear of each rearwardly extending plate in thediverging portion and forming arms extending laterally on each sidethereof. In the drawings, the torque tube as shown at 43 is formed fromplates welded together .and forming a pentagonal or five-sided box beam.The construction of the torque tube 43 is best understood by consideringit as a onepiece tube extending between pull arms 44, 44 so that it notonly extends laterally on each side of the diverging gooseneck arms 40,41 but also bridges the space between them.

A cutout is formed in the torque tube between the diverging arms 40, 41to provide a hoist housing for mounting the hydraulic hoists for raisingthe apron 33 and the bowl 24. This cutout is formed by cutting awayportions at least in the top and bottom walls of the torque tube 43between the diverging arms. However, this cutout is spaced forwardlyfrom rear wall 43a of the torque tube in Fig. 6 with the hoist housinghaving a plate 46 extending generally in the same direction as torquetube rear wall 43a and welded or otherwise secured to the top and bottomtorque tube walls at the rear of the cutout for forming a rectangularbox beam structure behind the cutout. Hence, the torque tube 43 is acontinuous box beam structure consisting of two box beams, eachpentagonal in shape, joined by a box beam rectangular in cross section.The hoist housing also includes side walls 47, 4'7 and a front wall 45welded to each other, to the arms 40 and 41 and to the torque tube 43wherever they meet to provide a strong structure. A sight opening 45a isprovided in the upper, central portion of the front hoist housing plate45 between the arms 40 and 41 and has a heavy, round, band rim-weldaround it to reinforce the opening. The purpose of the opening and therim-weld will be set forth more detail later in the specification.

g This torque tube 43 is located behind the rear wheels 21, 21 of thetractor so as to be closer to the ground for several reasons. The lowtorque tube has a low center of gravity so that the scraper has maximumstability when either empty or loaded. Also, as will be shown later inthe specification, the tractor driver can more readily see back into andaround the bowl in all operating positions.

The pull arms 44, 44 are shown in Fig. 4 as being welded or otherwisesecured to the outer ends of the torque tube 43 and extending rearwardlyto piyotalconnections at 44;, 44 with the bowl side ,walls. Fig. 9 showsone of the pull arms in section with anouter plate 44a, inner plate 44b,bottom plate 44d, intermediate wall 44c and downwardly inclined topplate 448 all welded or otherwise secured together to provide acontinuous box beam structure throughoutthe length of each pull arm. InFig. 8, either one or both plates 44c and 44d are extended forwardlyfrom the main part of the pull arm, wrapped around the torque tube 43 atits outer end, and welded thereto to form a strong structure. Therearward end of each pull arm 44 is pivotally attached at 44 to itsrespective bowl side wall 24a intermediate the ends of the bowl, aboutmidway between the front and rear thereof.

This pivotal mounting has two advantages; First, it concentrates all therear weight of the pull yoke and of the hydraulic cylinders (for raisingthe bowl and apron) onto the cutting blade 25 so that the scraperbowlwill readily dig even the most difficultto-cut soils. Second, thisconstruction enables a hydraulic hoist with a relatively short stroke tolift the scraper bowl 24 a large distance.

The pull yoke 22 forms a continuous box beam structure from the hitch 23to the pivots 44f, 44f since the diverging arms 4t and 41, the torquetube 43 with the hoist housing plates thereon, and the pull arms 44, 44each have a torsional resisting box beam structure and the componentplates are securely welded together. The housing for the hoists used inraising the apron 33 and the bowl 24 do not interrupt the continuity ofthe continuous box beam structuresince it is located between thediverging arms 40 and 41 within a cutout in torque tube 43, and thetorque tube 43 is a continuous box beam between the pull arms .44, 44including a rectangular box beam structure behind the cutout bounded atthe front and rear respectively by plate 46 and wall 43a inFig. 6 forkeeping the arms 4% and 41 spaced apart and for strengthening thestructure. This continuous box beam structure eliminates twisting andweaving betweenthe scraper assemblies and holds both ends of the cuttingblade 25 solidly during either the digging operation as in Fig. l, orthe spreading and ejecting operation, as in Fig. 3.

The means for raising the bowl and the means for raising the apron havemany parts in common and are clearly shown in Figs. 1 to 6 inclusive.Each has a power means or power unit including one or more hydraulichoists d, 51 and 52 with said hoists being located between the divergingarms 40 and 41 and being approximately laterally aligned on verticalaxes on the pull yoke 22. The two outer hoists 5d and 52 are operativelyconnected to the bowl 24 for raising it. The center hoist 51 isoperatively connected to the apron for moving it between its lowered orclosed position in Fig. 2 and its elevated or open position in Fig. 3.

At the lower end of the hoist housing, each hoist has a pair of supportbars 53 and 54 welded at opposite ends to the front and rearplates 45and 46 respectively of the hoist housing for tying the bottom of theseplates together and strengthening the pull yoke. The three pairs ofcrossbars, 53 and 54 (six crossbars in total), are mounted in the hoisthousing in horizontal alignment and each pair of bars ha's aligned holestherein formounting a pivot pin 55 therethrough. Three hoists requirethree pins 55, all shown as beiugcoaxially' a'ligued. The lower end ofeach hoist pivotally "securedon its pin 55 so that each hoist can pivotbetween the plates 45and 46 of the hoist housing in Fig. .6 asit raisesIor lowers the bowl or apron.

At the upper end of the hoist housing, a bridge truss 59 is welded tothe top of each of the arms and .41 and spans the distance therebetween.The lower surface of this truss 59 is also welded to the upper edge ofthe front plate of the hoist housing for making the pull yoke 22 a stillmore rigid structure. A plurality of lugs 59:} are welded to extendupwardly from the bridge truss 59 and have aligned bearing holestherethrough for rotatably supporting a one-piece pivot pin 60. Aplurality of levers 56, 57 and 58, one for each of the three hydraulichoists, are pivotally connected at their forward ends along a commonaxistosaid pin 60 and extend rearwardly toward the scraper bowl24. Eachlever consists of a pair of identically shaped, laterally spaced sidemembers, as shown in Fig. 4.

Each of the three hoists consists of a cylinder member and a pistonmember, see Fig. 6, wherein the cylinder member of hoist 52 isdesignated as 52a and the piston member as 52b. In the presentdisclosure the cylinder member 52a is pivotally mounted at its lower endon one of the three coaxiall-y aligned pins on the pull yoke while thepiston member 52b is pivotally mounted at its upper end to the lever 58between the lever side members and intermediate the ends of the lever.However, it should be apparent that the same lifting action on lever 58would result if members 52a and 52b were interchanged so that thepivotal mounting on the upper end of piston member 52!) was on pin 55 atthe lowest position of the hoist. The lower pivotal mountings of thehoists 5t), 51 and 52 are coaxial on the three pins 55.

The front and rear hoist housing plates 45 and 46 respectively havedefinite purposes in the structure. The front plate 45 ties together theinner surfaces of the two arms 40 and 4d, the front end of the twopentagonal torque tube shapes of torque tube 43 straddling the hoisthousing, and the truss 59 by being secured to each by welding. It shouldbe noted that the front wall 43b of the torque tube 43 may either be cutout between the side plates 47, 47 of the hoist housing, as illustrated,or be acontinuous plate between pull arms 44, 44 with the front hoisthousing plate 45 welded thereoveri The rear hoist housing plate 46separates the three hydraulic hoists from the bowl 24 to prevent theheaped load in the bowl from falling forwardly onto the hydraulichoists, not only when the scraper is being loaded in the conventionalmanner in .Fig. l, but also during top loading when a shovel means isdropping aload of .dirt into the bowl 24. The rear plate 46 preventsdirt spillage from the heaped scraper bowl load over the top ofthe apron33 into the'hoist housing. Lumps .of dirt in the hoist housingwould tendto jam the pivotal. movement of the hoists about the pins 55. However,if any does accidentally enter the hoist housing, it .can easily dropthrough the bottom opening between the side plates of the hoist housingand the various support bars 53 and.54.

Each of the hoists 50, 5d, and 52 is single acting and the hydraulicpressure fluid therein moves the piston memberl-out of the cylindermember and raises either the bowl or-the apron. The bowl .or apron islowered when no more pressure fluid is supplied to the hoist and thehydraulic fluid therein ispermitted to drain back throughthe originalsupply conduit. Thevertical alignment of the hoists adds the .weight ofthe piston member and lever to the. weight of either the apron or thebowl to force the pressure fluid from the hoist so that the apron orbowl will drop rapidly after the supply conduit begins to serve as adischarge conduit. l

The vertical alignment of the hoists has other advantages. The pistonmember and cylindermem ber are held 7 in alignment so that the amount offriction and wear therebetween is reduced and less leakage occurs.However, when leakage occurs, it is confined to a small area and theleaking fluid will run down the hoist and out the open bottom of thehoist housing to the ground since the hoists are located ahead of thescraper bowl 24. The pressure fluid cannot leak down onto the innersurface of the apron 33 to cause a dirt build-up thereon.

It should be noted that the bottom of the hoist housing is open not onlyto permit any dirt in the hoist housing or leaking pressure fluid fromthe hoists to fall through to the ground but also to permit easyservicing of the pivotal connections between the hoist and the pull yokeat pivot pins 55.

Means are provided for raising the bowl between a lowered deep-diggingposition, in Fig. l, and an elevated high-carry position, in Fig. 2.This means includes the power unit comprising hoists 0 and 52 andincludes a motion transmitting means operatively connected to the hoistsand the bowl 24 and movable in response to the hoists for raising thebowl a short distance with great force. The levers 56 and 58 of thismotion transmitting mean have already been discussed, and since eachlever has on its rearward distal end the same type of connection withthe bowl, only the connection on lever 56 in Fig. 2 will be described. Aconnecting link 62 is provided with its lower end pivotally secured tothe box beam 24b of the scraper bowl at 62a. The upper end of the link62, located between the side members of lever 56, has an elongated slot62b slidable on a pin on the lever 56 bridging the gap between said sidemembers.

A flexible cable is generally used instead of thi connecting link 62 toraise and lower the scraper bowl, but as the bowl lopes or bounces as itis being carried forwardly at a rapid rate in the Fig. 2 haulingposition, the cable of the prior art tends to "stretch and this in turnnot only multiplies the bounce but shortens the cable life. Our novelconnecting link 62 eliminates the troublesome, costly disadvantages of acable but preserves all the advantages thereof. The bowl can up floatwhen the cutter 25 is digging and scooping up rocky and stony earthsoils so that the cutting edge can feel its way during the diggingoperation. The connecting link 62 is a solid but slotted lift rod forcontrolling the bowl and cutting edge while permitting the desirable upfloat and eliminating the disadvantages of a cable.

The particular pivotal relationship between the parts provides thepresent scraper with many advantages. The pivots under discussion arelocated at the opposite ends of each lift hoist 50 or 52, at oppositeends of the lift levers 56 and 58, at opposite ends of each connectinglink 62, at 44f between the rearward end of each pull arm 44 and itsrespective bowl side wall 24a, at the rear wheels 31, 31, and at thehorizontal transverse axis pivotal connection of the hitch 23. First,approximately the same mechanical advantage exists throughout the wholelift range \between the lifiting force exerted by the hoist and thedownward force exerted on the links 62 by the bowl 2-4 and the load.Each link 62 remains at all times approximately parallel with itsassociated lift hoist, and the hoist and the link 62 form the same angleat any one position with their associated lever. Hence, the lever 'armfrom the pivot pin 60 extending perpendicular to the line of forceapplication by the hoist and the lever arm from the pivot pin 60extending perpendicular to the line of force application of link 62always bear the same pro portional relationship to each other.Therefore, an approximately constant fiuid pressure will lift the bowlthroughout its entire lift range since the pivotal connect-ions are sodesigned that lifting the bowl puts a uni form load on the hoists 50 and52. Second, the scraper has a lower overall height and better stabilityince the scraper lifts itself by its own bootstraps. When the cuttingedge 25 is lifted, the pull yoke 22 and the hydraulic hoists thereon arealso lifted but to a lesser degree 8 to obtain greater movement at thecutting edge 25 relative to the ground than the movement by the hoistswould indicate. The torque tube 43 can be mounted in a low position soas to cause only a minimum interference with the vision of the tractoroperator back into the scraper bowl 24.

Means is provided for raisingapron 33 between positions closing (-Fig.11) and opening (Fig. 3) the open front of the" scraper bowl 2-4. Thismeans includes the power unit or lift hoist 51 between and in line withthe bowl lift hoists 50 and 52. It also includes a motion transmittingmeans connecting said hoist S1 to the apron 33 and movable in responseto said hoist for raising said apron a greater distance per unitmovement of the hoist than the bowl is raised per unit movement of itshoist. This motion transmitting means includes not only the lever 57pivoted at its forward end on pivot pin 60 and pivotally mountedintermediate its ends to the hoist 51 but also a movement multiplyingmeans between the lever 57 and the apron 33. This means operativelyconnects the distal end of the lever 57 and the apron 33 for causing theapron to move at a more rapid rate than the distal end of the lever butin response to the movement of the lever. it includes in Fig. 3 a pulley64 rotatably mounted on the distal end of the lever between the leverside members and a flexible cable 65 operatively connected at one end tothe lower front edge of the apron at 66, operatively connected at theother end to the pull yoke at 67 and forming a bight over the pulley orsheave 64. The cable end connections 66 and 67 each consist of a quickknockout type cable wedge and ocket for securing the ends of the cablerespectively to the apron lift and to the back plate 46 of the hydraulichoist housing. The connection 66 also includes a pivot between thesocket and the apron lift so that the cable 65 can freely assume eitherthe position in Fig. 3 or the position in Fig. 2. Note that the flexiblecable 65 engages under the downwardly and rearwardly extending outwardlyconvex surface of apron 33 so that cable 65 is always kept in about thesame position in front of the bowl during raising of the apron.

It should now be apparent that the apron is raised a much largerdistance than the bowl when the hydraulic hoists moving each member areraised a uniform distance. Other types of movement multiplying means mayalso be used, if desired. For example, a different type of pulley andcable arrangement or other type of mechanism might give the desiredmechanical advantage. The pulley 64 could even be connected to thehydraulic hoist 51 in a different manner to provide the desired motiontransmitting mechanism between the hydraulic hoist and the apron.

The flexible cable 65 and the single acting hoist 51 eoact together topermit the apron lip to float down onto the stream of incoming earth inFig. l as the loading operation is finishing. Hence, the apron lip canfeel its way through the stream of earth so as to gently cut oif theflow of earth, while the scraper bowl is being lifted to the carryposition in Pig. 2, to prevent the earth from sliding out of the scraperbowl 24 between the scraper lip and the cutting edge 25.

Means is provided for moving the ejector 3'4 between its lowered,retracted loading position in Figs. 1 and 2 and its elevated dumpingposition in Fig. 3. This path of movement is clearly shown in Fig. 10.This means includes a power unit or hydraulic hoist '70, similar instructure to hoist 50, 51 and 52 previously described, having a cylindermember 7% and a piston member 76!). The rear end of the hydraulic hoist70 is pivotally connected on a diagonal brace 71 welded at its oppositeends respectively to therear axle housing 30 and to the scraper bowl 24at the laterally extending rear box beam 240.

Motion transmitting means is provided for accelerating the movement ofthe ejector over approximately the entire distance from the lowered orretracted position to the dumping position when the movement caused byits hydraulic hoist is at a constant rate. This means includes a lever72 pivotally mounted at its upper end at 72a under the laterallyextending box beam 24c. The opposite or lower end of the lever isadapted to make a relatively moving contact with the outside surface ofthe ejector by a means shown specifically in this disclosure as a roller73 rotatably mounted onits movable lower distal ends.

Since this lever 72 and pivot 72a are located under the box beam 24c andbehind the ejector 34 which contacts the box beam 24c at its upper edgein the loading position in Fig. l, and in the carrying position in Fig.2, the lever 72 and the pivot 72a are protected. They are only exposedduring the ejection operation as inFig. 3, when protection is notespecially necessary. When the parts assume the position in either Figs.1 and 2 and the bowl 24 is being loaded from 'the top by a power shovel,a lump of dirt accidentally falling behind the ejector 34 will bedeflected by the box beam 240 so as not to harm either the lever 72 orthe pivot 72a.

It should be noted that the lever 72 extends downwardly from the pivotalmounting 72a and conforms in shape to the outside surface of theejector. A hardened travel Wear plate '74 is welded to the bowl and hasan outside surface conforming in shape to the outside surface of theejector. During the ejection operation, the natural outer curvature ofthe ejector and the hardened wear plate 74 coacting with the roller73 onthe lever 72 play an important part in getting a desirable ejectionaction.

The front end of the hoist 70, at the left in Fig. 10, is pivotallymounted on the lever '72 intermediate its ends between pivot 72a androller 73. In the present disclosure, the hydraulic hoist cylindermember 76a is pivotally mounted to the brace 71 while the hydraulichoist piston member 7% is pivotally mounted to the lever 72. However, itshould be apparent that the same ejection action would be obtained ifthese hydraulic hoist members were interchanged in their pivotalmountings. Both the pivotal mounting between brace 71 and the hydraulichoist '70 and the pivotal mounting 72a are fixed with respect to thescraper bowl 24.

The ejection action should now be quite clear. As pressure fluid isadmitted into "the hoist '70 from the pressure source and control meanson the tractor 29 by way oi the conduit 700 in Figs. 2, 5 and 9, thecylinder member 7% and the piston member 7% are forced apart to cause arelative separation between the pivotal connections on the opposite endsof the-hoist 7%. This action causes the roller 73 on lever 72 torollalong the wear plate 74 to pivot ejector 34 upwardly around its pivotalconnection 34a on the bowl 24 from the retracted position in Fig. 2tothe dumping position in Fig. 3.

in Fig. 10, the mechanism is shown in several intermediate positions.Along are A, having its center at pivot point 72a, a series of dots havebeen placed, one dot designating the position of lever 72 for each unitdistance increase in separation between the pivotal end connec tions onthe hydraulic hoist 70. Corresponding positions of ejector '34 are shownby dots on arc B, having its center at pivot point 3461. Since thedistance in the counterclockwise direction between the first five dotson are B increases as ejector 34 moves toward the dumping position, theejector 34 must accelerate over this arcuate distance when there is auniform rate of extension of hydraulic hoist 79.

The distance between the fifth and sixth dot on arc B, measuring in thesame counterclockwise direction, however is not as large as the distancebetween the fourth and fifth dot so a slight deceleration takes place.Howover, most of the material is off of the ejector 34 by the time theejector reaches the fifth dot position on are B in its maximumacceleration. However, the forward momentum of any material stillremaining'on the ejector 34 will earryit forwardly and off of 'the'ejeotor as the ejector deeelerat'es between the fifth and sixth "dotposttions. .Also, ejector -34 engages stops on the bowl 24 in the sixthdot position to prevent further forward travel. The deceleration periodreduces the wear on these stops by reducing the forward rate of movementof ejector 34, but still when the ejector 34 engages the stops, thisaction still gives a good bump" against the stops for cleandumpingsticky earth from the inner surface of the ejector 34.

It should be noted that the length of the lever 72 be tween the pivotalconnection 72a and the roller 73 is greater than one-half the distancebetween the pivotal mounting of the ejector lever at 72a and the pivotalmounting of the ejector 34 to the scraper bowl 24 at 34a. It should alsobe noted that the relatively moving contact between the roller 73 andthe plate 74 is on opposite sides of the line connecting the pivotalmountings 34a and 72a when the ejector 34* is in the retracted or fullline position in Fig. 10 as compared with the dumping or dot-dot-dashline position. This relationship keeps the contact surface between theroller 73 and the plate 74 down to a minimum so that the length of plate74 need not be too long. In Fig. 10, the roller 73 moves forwardlytoward the ejector pivot 34a between the solid line and the dot-dashline position and then backs up along the plate '74 between the dot-dashand the dot-dotdash line positions.

The lever 72 and the connections thereto give a combined wedge androller leverage lift action to the ejector 34. At the start of thedumping action when ejector 34 is in the solid line position in Fig. 10and full load is on the ejector, a uniform rate of extension between theopposite pivotal connections on the hydraulic hoist 70 will move theejector 34 slowly and with a maximum lifting force. As the load on theejector 34 decreases, it will move at a faster rate. Hence, the speed ofmovement of ejector .34 varies approximately inversely with the load,and the force exerted by the hydraulic hoist on the ejector variesapproximately directly with the load being moved during the ejectionstroke.

When t-heejector 34 is in the dot-dot-dash line dumping position in Fig.10, it is approximately or nearly balanced over the pivotal connections34a. Since the hydraulic hoist 70 is a single acting hoist, a springreturn means must be provided for pulling back the ejector from thedot-dot-dash line position to where the Weight of the ejector becomesfully effective to drop it to the retracted or solid line position inFig. 10. This spring return means is specifically shown in the presentdisclosure as including a spring 76 connected at one end to the bowl 24in the zone of the lever pivot 72a and a-t't-he other end to anapertured lug 77 "welded to the outer surface of "the ejector. The wordzone is intended to mean any point in the immediate neighborhood of thepivot 72a providing the desirable functions attributed to this spring.

It should be noted that the spring 76 does not greatly stretch in lengthin view of the long travel or" the ejector 34. Since the distancebetweenthe end connections of spring 76 is approximately the same as or lessthan the distance between the lever pivot point 720 and its re1ativelymoving contact With the ejector by roller 73, when the ejector is in itssolid line retracted position, the spring 76 does not materiallyincrease in length, to store force for returning the ejector34 to theretracted position, until the ejector approaches its dumping positionwherein it is approximately balanced over the pivotal mounting, as shownin the dot-dotdash position in Fig. 10 The spring 76 is normally relaxedand does not increase in length in direct proportion with the movementof the ejector 34 to create aforce opposing the power stroke of thehydraulic hoist 7%. For example, when the ejector is in thedot-dashposition the spring would be stretched less than when theejeotoris inthe solid line position. However, thespring' 76 gives a strong pull whenthe ejector-34 is in the :dot-dot-dash line position toUmove itclockwise from its approximately or nearly balanced position over thepivot 34a. It should be noted that the laterally extending box beam 240in Fig. 10 and the ejector 34 in the solid line position protect notonly lever 72 but also spring '76 during loading (Fig. 1) and carrying(Fig. 2). This is especially desirable when the scraper bowl 24 is beingtop-loaded by a power shovel.

Figs. 1 to 4 inclusive disclose that the parts of this scraper arearranged for maximum vision by the tractor operator back into and aroundscraper bowl 24. This increased visibility with minimum sightinterference is possible only because of the novel design of the pullyoke 22 and of the means for raising the scraper bowl 24 and the apron33.

The tractor operator has a clear line of sight under the torque tube 43between the rear tractor wheels 21, 21 and between the rearwardlydiverging gooseneck arm 45 and 41 whenever necessary. During loading inFig. 1, he has a clear line of sight in the zone between lines C and Dover the rear of the tractor frame and under the torque tube 43. Thecutting action at the cutting blade 25 and the flow of soil into thescraper bowl 24 can be easily observed. During hauling in Fig. 2 afterthe scraper bowl '24 has been raised, the tractor operator can readilysee in the zone between the sight lines E and F to be sure that there issufficient clearance under the scraper bowl at all times. During dumpingin Fig. 3, the tractor operator can readily see in the zone between thelines G and H to control the dumping and spreading operation as the dirtemerges from the scraper bowl 24.

During the loading operation in Fig. 1 when the load of earth isbuilding up within the scraper bowl 24, the tractor operator can readilysee over and between the lift levers 56, 57 and 58 in the zone boundedby lines I and J in Fig. 1 over the front hoist housing plate 45 backinto the upper part of the scraper bowl 24. The hydraulic hoists 50, 51and 52 are collapsed and out of sight during the digging or loadingoperation in Fig. 1 when unrestricted rear vision is most needed. Theleverage is such that the hydraulic hoists are still within the heightof the gooseneck arch of the pull yoke. The levers 56, 57 and 58 extendrearwardly from their pivotal connection 6i) in the direction of theline of sight of the tractor operator looking toward the scraper bowl soas to cause a minimum interference with his line of sight. The leversare in their lowest position, being inclined below the horizontal,during loading in Fig. 1 so that they do not interfere with the rearview of the operator above the pull yoke. The hydraulic hoist 50, 51 and52 are extended only in the hauling position in Fig. 2 and the dumpingposition in Fig. 3 when unrestricted rear vision into the upper portionof the scraper bowl 24 is not needed.

The tractor operator can see between the diverging arms 40 and 41 inFigs. 1, 3 and 4 back into the scraper bowl 24. He can see through thesight opening 45a in Fig. 6 between the hydraulic hoists 50, 51 and 52in Figs. 4 and 5 back into the scraper bowl 24 while loading (Fig. 'l)and dumping (Fig. 3). His line of vision is within the zones bounded bylines KL and lines MN in Fig. 4. The cutout in the torque tube 43 forthe hoist housing has been especially made so that the hydrauliccylinders 50, 51 and 52 are located at their rearmost position for thewidest transverse in-line spacing to provide maximum sight spacingbetween each hoist. Typical lines of vision back into the scraper bowland through the sight opening 45a are shown at O and P in Figs. 1 and 3.While the operator is looking back through the sight opening 45a intothe scraper bowl, he can also watch the action of the hoists 50, 51 and52 to be sure that they are operating correctly.

The sight opening 45a in Fig. 6 has still another purpose. The pressurefluid conduits from the pressure source and the control means on thetractor lead back along the inner side of one of the gooseneck arms 40or 41 through this opening 45a to the hydraulic hoists 50, 51, 52 andthe ejector hoist 70. The conduits to hoists 50, 5'1 and 52 areconnected to the front sides thereof in Figs. 5 and 6 as the level ofthe opening 45a for quick and easy access for detaching or attaching theconduit to each hydraulic hoist. The round, band rim-weld around theedge of opening 45a provides a round guide surface for the conduits forpreventing damage to them.

If the diverging gooseneck arms 40 and 41 were replaced by a unitary boxbeam, as mentioned earlier in the specification, it would be impossible'for the tractor operator to see through the box beam in the same mannerthat he could see between the diverging arms 40 and 41 back through thesight opening 45a and between levers 56, 57 and 58 into the scraper bowl24.

The tractor operator can also see back into the scraper bowl 24 bylooking outside of the rearwardly diverging gooseneck arms 40 and 41above the line Q in Fig. 4 and below the line R. This is shown in Fig. 3as line S to the outside of arm 41 and over torque tube 43 back into thescraper bowl 24 when the scraper is dumping the load because of the lowposition of the torque tube 43. The arms 40 and 41 diverge in thedirection of sight of the tractor operator back into the scraper bowl toform a minimum area of sight interference for He has clear vision oneach side of the gooseneck arms since the hydraulic hoists 50, 51 and 52are between the arms 40 and 41 and behind the gooseneck arch.

Windows 33b, 33b are provided in the apron 33 spaced outwardly from eachdiverging arm 40 or 41. The tractor operator can readily see through thewindows 33b, 33!) back into the scraper bowl during the loadingoperation in Fig. 1 to see when a full load has been scooped up. Eachwindow has a screen mesh thereover to prevent the scraper load fromdropping out of the bowl. Each window is elongated vertically or in thedirection of apron opening movement so that the tractor operator canreadily see through it for different apron openings. Soft materials,such as coal, sand, etc, require that the apron be raised higher thanfor some other materials. A high apron position with a large diggingthroat permits a deep cut to be taken and a large volume of material toenter the scraper bowl 24.

Increased visibility is created by several factors in the design, amongthem being the low position of torque tube 43, the novel motiontransmitting means connecting the hydraulic hoists to the apron andbowl, and the location of the hydraulic hoists in a cutout in the torquetube 43 between the rearwardly diverging gooseneck arms 40 and 41.

The low position of the torque tube 43 behind the tractor drive tires21, 21 permits the tractor operator to see into the scraper bowl 24 andto see the pusher tractor back at the pusher bumper 28, if necessary. Hecan see not only through the sight opening 45a in the hoist housing butalso over the low torque tube 43 outside of the rearwardly divergingarms 40 and 41. It also gives the scraper good stability whether emptyor loaded. Of course, the low position of the torque tube 43 requires agooseneck arch in the rearwardly diverging arms 44) and 41 to clear therear wheels 21, 21 during turning.

The low placement of the torque tube 43 is made possible by otherfeatures of the design. First, the pivotal relationship between thescraper parts including the pivots located at the opposite ends of eachlift hoist, 50 or 52; at opposite ends of the lift levers 56 and 58; atopposite ends of each connecting link 62; at pivot 44 between therearward end of each pull arm 44 and its respective bowl side wall 241;;at the rear wheel 31, 31; and at the horizontal transverse axis pivotalconnection of the hitch 23. The scraper has a lower overall height andbetter stability since the scraper lifts itself by its own bootstraps.When the cutting edge 25 is lifted, the pull yoke and the hydraulichoist thereon are 13 also lifted but to a lesser degree to obtaingreater movement at the cutting edge relative to the ground than themovement by the hoists per se would indicate. The low torque tube 43,possible with thisdesign, causes minimum interference with the vision ofthe tractor operator back into the scraper bowl.

Second, the mechanical advantage of the motion transmitting means withtheir placement between each hydraulic hoist and associated bowl orapron makes possible a low torque tube. The hydraulic hoists G, 51 and52 with the motion transmitting means secured to each must exert "amaximum lifting force on the bowl and apron for easy and fast operation.The hoists, lift levers 56, 57 and 58, the pivot pins thereon, and thepulley 64 must be grouped together into a compact unit to create minimuminterference with the sight of the operator back into the scraper bowlbut still all parts must be readily accessible for disassemblyandrepair. Since the hoists are mounted between the rearwardly divergingarms 40 and 41, they must be located in a cutout in the torquetube'so asto be positioned as far to the rear as possible so that the tractoroperator can sight through the opening 45a in the hoist housing 'andbetween the hoists back int'o'ihe'scraperbowl 24.

The three means for raising the bowl, apron and ejector each includeidentical hydraulic hoists 50, 51, 52 and 7t) and include motiontransmitting means between said hoists and the apron, bowl or ejector.

Each hoist is identical in construction and interchangeable with each ofthe other hoists. Each hyd'raulic hoist is single acting and has asingle pressure fluid conduit connected with the pressure source and thecontrol means operable by the tractor operator. "lhepre'ssure 'fluidlifts the bowl, apron or ejector while the weight of each assemblycauses it to lower as the pressure is decreased in its conduit and thepressure fluid is permitted to escape from the hydraulic hoist backto amain reservoir. Each hydraulic hoist has the same length working strokeandbore size and has a cylinder member and a piston member with eachmember havused to advantage in the present digging and carrying scraperis completely disclosed in the copending U. S. patent applicationentitled Hydraulic Hoist Construction, to Raymond Armington and HaroldC. Schindler, Serial No. 71,056, filed January 15, 1949, now abandoned,and vin the copending continuation-id part application thereof,Serial'No. 277,176, now Patent No. 2,692,584, granted October :26, 1954.The operations of raising and lowering of the scraper bowl 24, ofmovingthe apron 33, and of moving the ejector 34 are. performed independentlyof each other. Each is operable independently so the apron or bowl orejector may be moved without moving the other two mentioned movablescraper parts. Three pressure conduit line controls are provided on thetractor for manipulation by the tractor operator, one controlling theapron liftthydraulic-hoist 51, one controlling the bowl lift hydraulichoists 50 and 52, and the other controlling the ejector lift hydraulichoist '70.

The motion transmitting means between each hoist and its associated,part for the bowl, apron and ejector even have features in common. Eachincludes a lever pivotally mounted at one endto one of the large scraperparts, either the pull yoke 22 or the bowl structure,

pivotally mounted intermediate its ends to its associated sure can beused even though the load, distance of movement, and desirable rate ofmovement differs for the bowl, apron and ejector. Since the hydraulicpressure for each hydraulic hoist is substantially the same under fullload conditions, the force exerted by the hoists to raise, at full load,either said apron or ejector or bowl divided by the mechanical advantageof the associated motion transmitting means for each hydraulic hoistbears a relationship of approximately 1:1:2 respectively for the raisingmeans of the apron, ejector and bowl. In other words, this ratiocorresponds to the number of hoists used-one for the apron, one for theejector and two for the bowl-since the working pressure at full load ineach hoist is the same.

Although approximately identical operating pressures and identicalhydraulic hoists are used, the force, length of movement and desirablespeed of movement of the bowl, apron and ejector vary. Hydraulic hoists5i) and 52 for raising the scraper bowl 24 must raise the bowl a shortdistance with great force since they must raise not only the heavy bowlbut the full load therein. The load on the scraper bowl hoists issubstantially the same throughout the range of'their movements and thelever arms 56 and 58 havebeen designed so that each forms the same anglewith its connecting link 62 as it forms with its associated hoist at thesame time. Although these angles change as the bowl is raised,approximately the same proportion always exists between the length ofthe lever arm extending perpendicular from the hydraulic hoist to thepivot 60 and the length of the lever arm ex tending perpendicular fromthe link 62 so that uniform hydraulic pressure in the lift hoists causesa uniform lifting force to be applied to the scraper bowl.

In contrast, the apron 33 must move a greater distance per unit movementof its hydraulic hoist 51 than the bowl per unit movement of itshydraulic hoists. The hydraulic hoist 51, having the same length ofstroke as hydraulic hoists 50 and 52, not only must be able to raise theapron the same height as the bowl lift hoists lift the bowl to keep thesame relative position therebetween but also must be able to lift theapron from its closed or full load position in Fig. 11 to its elevatedand open position in Fig. 3. It must be able to raise the apron at fullload for desirable scraper operation about twice the distance at abouttwice the speed of said bowl raising movement. Hence,the apron 33requires only about one-quarter of the lifting force required by thescraper bowl 24.

The desirable movement of the ejector 34 is entirely different. Incontrast with the uniform load on bowl hoists, the load on the ejector34 decreases as it is moved from the solid line position to thedot-dot-dash line position in Fig. 10 as the material slides: cit of theinner surface of the ejector. To cut dumping time, accelerating movementof the ejector as it moves forwardly is desirable. As fully disclosedpreviously in the specification, the ejector 84 accelerates overapproximately the entire distance from the full load soiid lineretracted position to the dot-dot-dash line dumping position when thehydraulic hoist expands at a constant rate. There is a slow movementwith maximum force at the start of the dumping action at full load. Thespeed of movement increases as theload on the ejector becomes lighter sothat the speed varies approximately inversely with the load on theejector and the hydraulic hoist 7i) exerts through lever 72 a force onejector 34 varying approximately directly with the load on the ejectorbeing moved.

The advantages in using interchangeable hydraulic hoists whilemaintaining the most desirable operating action of the scraper bowl 24,the apron 33 and the ejector 34 are many. Interchangeable hydraulichoists lower manufacturing costs since the manufacturer can machinestandard parts in larger lot sizes, carry a smaller inventoryioffinishedpar'ts and raw materials, and assemble the hoists in less timesince labor saving devices can be justified in view of the largerproduction reducing amortization costs per piece on such devices. Thescraper has a lower upkeep cost since the manufacturer, distributor anduser can carry a smaller inventory of hydraulic hoists and componentparts while always being sure that they will have the needed part at theright time when a breakdown occurs. Only a single conduit connects eachhoist with the control means on the tractor since each hoist is singleacting and not double acting.

Fig. 11 shows the present lever type digging and carrying scraper withapproximate working dimensions set forth thereon so that we may considerthe approximate hydraulic operating pressures and range of movement ofeach part based on reasonable estimates of the loads generallyencountered.

The force involved in the bowl lift can easily be calculated. Thecutting edge 25 has about a 46" vertical movement, including a 14" digbelow ground and a 32" lift above ground. The lift beam (front of bowl)travels I/ 46= 56 travel The ball joint 44 travels The pull yoke travelsX46"=36 travel with respect to the ground from hitch 23 to ground atdimensions from the hitch 23 to the lift link 62. The lift or connectinglink 62 travels 56"24"=32 travel with respect to the pull yoke 22.

The load on the end of the lift lever is 155 20,000# (load On hitch 23)64 (ball joint 44 f to link 62) X2 (levers) on each lift link 62 and oneach lift lever 56 and 58.

The approximate full load on the apron lift lever 57 can be easilycaclulated. Assuming a 12,000# load at the center of gravity of theapron, then the cable load is The pulley 64- on the end of the liftlever 57 doubles the travel of cable 65 and also doubles the load on thepulley or distal end of the lever 57 and this load is 2 8,000#=16,000#load 12,000# =8,000# load 2+24 (yoke travel with ground) 115 orapproximated in another manner as being equal to the relative travelbetween the front portion of the apron 16 (near the front end of thebowl) relative to the ground plus the maximum apron opening As to theejector, it must move through a 66 angle between the solid line positionand the dot-dot-dash line position in Fig. 10 about the pivot 34a andthis requires a 59 angular travel of the ejector dump lever 72 about itspivot 72a. From a vector force diagram, it has been determined that aforce of 15,600# is required at the roller 73 to lift the full load inthe ejector 34.

Each hydraulic hoist has a 20" stroke with a piston having a 7%"diameter or a total cross sectional area of 49 sq. in. At full load, thefollowing hydraulic pressures exist. In the bowl lift hoists 50 and 52,the hydraulic pressure required without considering starting inertia orfriction is 49 sq. in.X20 In the apron lift hoist 51, the pressurerequired without considering the starting inertia or friction is In theejector hydraulic hoist 70, the pressure excluding the starting inertiaor friction is it should be realized that the friction load in dumpingthe ejector 34 is much higher than in either the bowl or the apron liftbecause of the wedging action.- The actual pressure required to dump theejector is usually the highest of the three pressures. Both the apronand ejector moving mechanisms contain parts causing frictional dragwhereas the bowl hoist is directly connected. Therefore, in actualpractice, the hydraulic fluid pressure developed in the ejector andapron hoists and 51 is larger than the theoretical calculation shown.

Assuming the 20" stroke for each hydraulic hoist, the travel of the bowland apron can be approached in another way. The travel of the lift link62 was before given as 32 and proves to be the same here and the travelof the sheave end or pulley end of the lever 57 before given as 39" nowcomes out approximately the same =788 pounds per sq. in.

635 pounds per sq. in.

=620 pounds per sq. in.

It was previously pointed out that plate 74 can be of relatively shortlength due to the back and forth movement of roller 73 thereon duringthe ejection stroke, as shown in Fig. 10. With the above dimensions, theroller moves 14 toward pivot 34a between the solid line position and thedot-dash line position and then moves 5 to 6" back away from the pivot34a between the dot-dash line and the dot-dot-dash line positions.

Although each of the hydraulic hoists shown as being a single actinghoist and being returned to its closed position by either the spring andthe weight of the part being raised or the weight of the part alone, itshould be understood that the hoists could be double acting hoists ifdesired. However, the single acting hoist is preferred since it requiresonly one pressure line and for other obvious reasons thoroughly setforth heretofore in the specification.

The afore-rnentioned dimensions and the structural parts of the levertype scraper set forth heretofore also give a good forward weightdistribution of the scraper and its earth load onto the tractordrivewheels 21, 21 which is so vitally necessary for the maximum tractivcdrive effort.

Although the front of the scraper pull yoke 22 is shown as beingpivotally attachedto a tractor bya hitch 23,, other structuresequivalent to the tractor and hitch could be used. The front of the pullyoke 22 could be securedsby hitch 23m an equivalent hitch to any othertype wheeled supportingjframe, inaddition to the specific type shown astractor 20 in the drawings, which supporting frame has steerable wheelswith the wheels adjacent the hitch adapted to pass under the gooseneckarch of the pull yoke 22 during turning. The wheeled supporting framenot only supports the front of the pull yoke and scraper but alsocontrols the direction of its movement. The motive power, now furnishedby tractor 20, could be provided by a driving motor at the front or rearof the scraper or in any other desirablelocation Com monly; this type ofscraper has thepull yoke connected by" a hitch to a two-wheel dolly, inthe position of wheels 21, and a separate endless-track tractor or othermotive power exerts the pull.

What we claim is: V j

1. In a'dig'ging and carrying scraper, a bowl having an open front andhaving an ejector'forf dumping the contents of said bowl, an apron forclosing said open front, means for raising said bowl between lowered:and elevated positions, means for raising said apronnbctween positionsclosing and opening said open front, meansl for raising. said ejectorbetween a lowered retracted position and anelevated dumping position,each of said means including an interchangeable single acting hydraulichoist power unit in operative connection therewith forperforming theraising movement while the weight of the respectiye parts returns theapron or bowlor ejectorjtolits lowcred position when its respectivehydraulic hoist power unitisfde-activated, the hydraulic hoist powerunits being operable independently so that the apron or the b owlor theejector may be moved without moving the other two last-mentioned movablescraper parts, each hydraulic hoist power unit having the same lengthworking stroke, said means for raising said bowl including two of saidhydraulic hoist power units with each operatively connected to a motiontransmitting means movable in response thereto with the last-mentionedmeans connected to said bowl for raising it at full load a shortdistance with great force, said means for raising said apron including amotion transmitting means movable in response to its associatedhydraulic hoist power unit and operatively connected to said apron forraising said apron at full load about twice the distance at about twicethe speed of said bowl raising movement and exerting about one quarterthe lifting force required to lift said bowl, said means for raisingsaid ejector including a motion transmitting means movable in responseto its associated hydraulic hoist power unit and operatively connectedto said ejector for raising it at full load at a speed varyingapproximately inversely with the load and with a force varyingapproximately directly with the load being moved during ejection and foraccelerating its movement as it moves over approximately the entiredistance from the retracted position to the dumping position when itsassociated hydraulic hoist power unit moves at a constant rate.

2. In a digging and carrying scraper, a yoke for attachment to a wheelsupporting frame, a bowl comprising a bowl body having an open front andpivotally connected intermediate its ends to said yoke and having anejector for dumping the contents of said bowl pivotally connected tosaid bowl body and forming bottom and rear walls for said bowl, an apronpivoted to said bowl adjacent the pivotal connections of said yoke forclosing said open front, means on said yoke for raising said bowlbetween lowered and elevated positions, means on said yoke for raisingsaid apron between positions closing and opening said open front, meansfor raising said ejector between retracted position and dumpingposition, each of said means including an interchangeable single actinghydraulic hoist power unit in operative connection therewith for powermovement between positions in one, direction and for gravity return inthe opposite direction, the hydraulic hoist power units each beingoperable independently sothat the apron or the bowl or the ejector maybe moved without moving the other two last-mentioned scraper parts andeach having the same length working stroke, each hydraulic hoist powerunit having cylinder and piston members with a pivotal connection oneach member, said means for raising said apron and bowl each including alever pivoted at one end to said yoke and including one of saidhydraulic hoist power 'units with one of its pivotal connections on saidyoke and theother on its associated lever intermediate the oppositeends, thedistal end of the bowl raising lever beingoperativelyconnected'to saidbowl body, the distal end of the apronraising lever having movement multiplying means operatively connected tosaid apron for causing it to move at a more rapidrate and over a greaterdistance than said last-mentioned distal end, said means for raisingsaid ejector including a leverl having at one end a pivotal connectionfixedwithrespect to the bowl body and having its other end adapted tomake a relatively moving contact withtheoutside surface of said ejector,the hydraulic hoist power*unit for moving said ejector having one of itspivotal connections fixed with respect to the bowl body and the otherintermediate the opposite ends of said ejectordever; whereby the ejectoraccelerates over approximately its entire movement from retracted todumping position when the movement caused by its associated hydraulichoist power unit is at aconstant rate. I

3; In a digging and carrying scraper having a scraper bowl Wih an openfront, an apron connected to said bowl for relative'movement betweenpositions closing or opening' said open front, a pull yoke having ahitch member at its front end forpattachment to a tractor between itsrear wheels for moving saidscraper, said pull yoke having rearwardlyextending side walls and having a transversely extending torque tubesecured to the rear of said walls to extend laterally on each sidethereof and having means connecting said torque tube to said bowl forrelative movement therebetween; the combination wherein said pull yokewalls diverge in the rearward direction and form a gooseneck portionarched upwardly sufficiently for clearing the rear wheels of saidtractor during turning, a plurality of hydraulic hoists with each havingan approximately vertical axis and being located at the rear of saidpull yoke between said diverging walls and operatively connected to saidbowl and apron for raising said bowl and for moving said apron betweensaid closing and opening positions, each hydraulic hoist having cylinderand piston members with one of said members being pivotally mounted tothe lower rear portion of the gooseneck portion, said operativeconnections including a plurality of levers pivotally connected to saidgooseneck portion near its upper portion and extending rearwardly in thedirection of sight of the operator on said tractor looking toward saidbowl, each lever being pivotally connected to the other of said membersof its associated hoist, one lever having rotatably mounted at itsrearward end a pulley over which a run of cable extends between fixedconnections respectively to said yoke and apron, another of said leversbeing operatively connected to said bowl by a rigid link extendingbetween said bowl and the rearward end of said other lever, wherebyoperation of said hoist will cause said apron to move upwardly to agreater extent at greater speed than said bowl.

4. In a digging and carrying scraper, as set forth in claim 3, whereinsaid levers are inclined downwardly from their pivotal connection tosaid gooseneck during loading so that they do not interfere with therear view of the operator above the pull yoke.

5. In a digging and carrying scraper having a scraper bowl with an openfront, an apron connected to said bowl for relative movement betweenpositions closing or opening said open front, a pull yoke having a hitchmember at its front end for attachment to a tractor for moving saidscraper, said pull yoke comprising a pair of diverging arms rearwardlyextending from said hitch member, a transversely extending torque tubesecured to the rear of each arm and extending laterally on each sidethereof, and means connecting said torque tube to said bowl for relativemovement therebetween; the combination wherein said torque tube has acutout formed by cutaway portions in the tube walls between saiddiverging arms, approximately vertically extending hoists in said cutoutfor raising said bowl and for moving said apron between said closing andopening positions, said cutout spaced forwardly from the rear wall ofsaid torque tube, a wall secured to the torque tube walls surroundingsaid cutout for housing said apron and bowl hoist moving means, at leastone sight opening in said last-mentioned wall, whereby the tractordriver can see through said opening into the housing in said cutout forobserving the action of the'hoists and can see between said hoists backinto the bowl while loading and dumping and can see the bottom "of thebowl under the torque tube while loading, dumping and hauling.

6. In a digging and carrying scraper, as set forth in claim 5, whereineach hoist is pivotally mounted to said yoke with said plate preventingdirt entry and jamming of the pivotal hoist movement.

7. In a digging and carrying scraper, a scraper bowl having a bottom andback and spaced apart side walls and an open front, an apron connectedto said bowl for relative movement between positions closing or openingsaid open front, a yoke having a hitch member for attachment to awheeled supporting means at its front end for moving said scraper, saidyoke comprising a portion having outer side walls diverging in therearward direction, a transversely extending torque tube secured to therear of said first-named portion bridging the space between saiddiverging walls and extending laterally on each side thereof, saidtorque tube being box beam in form and having a cut-out formed bycut-away portions in its top and bottom walls between said divergingwalls for housing means for raising said bowl and for'moving said apronbetween said closing and opening positions, said cut-out being spacedforwardly from the rear wall of said torque tube, a surrounding wallsecured to the torque tube walls surrounding said cut-out for housingsaid apron and bowl moving means and diverging in the up ward directionto permit pivotal movement thereof, two arms, each of said arms securedat its forward end to one of said laterally extending portions of saidtorque tube and at its rearward end pivotally attached to one of saidbowl side walls, said arms and torque tube and diverging portion beingeach formed of box beam construction for providing a continuous rigidbox beam between the hitch member and the pivotal connections of thearms with the bowl sides.

References Cited in the file of this patent UNITED STATES PATENTS2,154,503 French et a1. Apr. 18, 1939 2,227,433 Berner Jan. 7, 19412,252,763 French Aug. 19, 1941 2,304,076 Davidson Dec. 8, 1942 2,304,527Armington et al. Dec. 8, 1942 2,345,313 Armington et al Mar. 28, 19442,406,826 French et al Sept. 3, 1946 2,529,848 Murray Nov. 14, 19502,567,118 Murray Sept. 4, 1951 2,573,765 Gustafson Nov. 6, 19512,650,440 Quartullo Sept. 1, 1953 2,662,312 Kadz Dec. 15, 1953 2,674,815Adams Apr. 13, 1954

